Engine problems possibly caused U.S Navy Osprey crash: report

WASHINGTON (Reuters) - The fatal crash last May of an Osprey tiltrotor aircraft built by Boeing Co and Textron Inc’s Bell Helicopter was possibly due to a loss of power caused by ingestion of sand into the engines, Aviation Week magazine reported, citing a U.S. Navy report.

The U.S. Navy is continuing to investigate the Hawaii crash, which killed two U.S. Marines and injured 20 other occupants. In the meantime, it has imposed restrictions on Osprey MV-22 landings under restricted visibility conditions, the magazine said.

The crash has raised new questions about the safety of the aircraft which takes off like a helicopter and then rotates its propellers to fly like a plane.

Development of the plane was nearly canceled after the deaths of 23 Marines during flight testing in 2000, but its speed and range have made it very popular in recent years.

The U.S. Navy report comes months after the Navy said it would use the Osprey to deliver people and cargo to aircraft carriers, a move that will help Boeing and Bell extend production of the planes from 2020 to 2025.

The Osprey is also vying for large foreign sales, including a $332.5 million sale of five aircraft to Japan in July.

The power loss in the latest accident may have been caused by sand containing reactive minerals such as calcium, magnesium and silicon which "melted in the engine's combustor and solidified on the fixed first-stage turbine vane", Aviation Week said, citing a Sept. 9 preliminary status report by U.S. Naval Air Systems Command, or Navair.

The U.S. Navy report also found three earlier “surge events related to reactive sand” and six additional “rapid power loss events” that occurred in areas where there is sand with reaction minerals, Aviation Week said.

A Navair spokesman, Billy Ray Brown, declined comment since the investigation still under way.